Electrodynamic apparatus and method of manufacture

ABSTRACT

Electrodynamic apparatus such as a motor, generator or alternator is configured having a stator core assembly formed of pressure shaped processed ferromagnetic particles which are pressure molded in the form of stator modules. These generally identical stator modules are paired with or without intermediate modules to provide the stator core structure for receiving field winding components. In one embodiment, two sets of the paired stator modules are combined in tandem to enhance operational functions without substantial diametric increases in the overall apparatus.

CROSS-REFERENCE TO RELATED APPLICATIONS STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

Not applicable.

BACKGROUND OF THE INVENTION

Investigators in the electric motor arts have been called upon to significantly expand motor technology from its somewhat static status of many decades. Improved motor performance particularly has been called for in such technical venues as computer design and secondary motorized systems carried by vehicles, for example, in the automotive and aircraft fields. With progress in these fields, classically designed electric motors, for example, utilizing brush-based commutation, have been found to be unacceptable or, at best, marginal performers.

From the time of its early formation, the computer industry has employed brushless d.c. motors for its magnetic memory systems. The electric motors initially utilized for these drives were relatively expensive and incorporated a variety of refinements, for instance as necessitated with the introduction of rotating disc memory. Over the recent past, the computer industry has called for very low profile motors capable of performing in conjunction with very small disc systems and at substantially elevated speeds.

Petersen, in U.S. Pat. No. 4,745,345, entitled “D.C. Motor with Axially Disposed Working Flux Gap”, issued May 17, 1988, describes a PM d.c. motor of a brushless variety employing a rotor-stator pole architecture wherein the working flux gap is disposed “axially” with the transfer of flux being in parallel with the axis of rotation of the motor. This “axial” architecture further employs the use of field windings which are simply structured, being supported from stator pole core members, which, in turn, are mounted upon a magnetically permeable base. The windings positioned over the stator pole core members advantageously may be developed upon simple bobbins insertable over the upstanding pole core members. Such axial type motors have exhibited excellent dynamic performance and efficiency and, ideally, may be designed to assume very small and desirably variable configurations.

Petersen in U.S. Pat. No. 4,949,000, entitled “D.C. Motor”, issued Aug. 14, 1990 describes a d.c. motor for computer applications with an axial magnetic architecture wherein the axial forces which are induced by the permanent magnet based rotor are substantially eliminated through the employment of axially polarized rotor magnets in a shear form of flux transfer relationship with the steel core components of the stator poles. The dynamic tangentially directed vector force output (torque) of the resultant motor is highly regular or smooth lending such motor designs to numerous high level technological applications such as computer disc drives which require both design flexibility, volumetric efficiency, low audible noise, and a very smooth torque output.

Petersen et al, in U.S. Pat. No. 4,837,474 entitled “D.C. Motor”, issued Jun. 6, 1989, describes a brushless PM d.c. motor in which the permanent magnets thereof are provided as arcuate segments which rotate about a circular locus of core component defining pole assemblies. The paired permanent magnets are magnetized in a radial polar sense and interact without back iron in radial fashion with three core components of each pole assembly which include a centrally disposed core component extending within a channel between the magnet pairs and to adjacently inwardly and outwardly disposed core components also interacting with the permanent magnet radially disposed surface. With the arrangement, localized rotor balancing is achieved and, additionally, discrete or localized magnetic circuits are developed with respect to the association of each permanent magnet pair with the pole assembly.

Petersen in U.S. Pat. No. 5,659,217, issued Aug. 19, 1997 and entitled “Permanent Magnet D.C. Motor Having Radially-Disposed Working Flux-Gap” describes a PM d.c. brushless motor which is producible at practical cost levels commensurate with the incorporation of the motors into products intended for the consumer marketplace. These motors exhibit a highly desirable heat dissipation characteristic and provide improved torque output in consequence of a relatively high ratio of the radius from the motor axis to its working gap with respect to the corresponding radius to the motors' outer periphery. The torque performance is achieved with the design even though lower cost or, lower energy product permanent magnets may be employed with the motors. See also: Petersen, U.S. Pat. No. 5,874,796, issued Feb. 23, 1999.

The above-discussed PM d,c, motors achieve their quite efficient and desirable performance in conjunction with a multiphase-based rotational control. This term “multiphase” is intended to mean at least three phases in conjunction with either a unipolar or bipolar stator coil excitation. Identification of these phases in conjunction with rotor position to derive a necessary controlling sequence of phase transitions traditionally has been carried out with two or more rotor position sensors. By contrast, simple, time domain-based multiphase switching has been considered to be unreliable and impractical since the rotation of the rotor varies in terms of speed under load as well as in consequence of a variety of environ mental conditions.

Petersen in application for U.S. patent Ser. No. 10/706,412, filed Nov. 12, 2003, entitled “Multiphase Motors With Single Point Sensing Based Commutation” describes a simplified method and system for control of multiphase motors wherein a single sensor is employed with an associated sensible system to establish reliable phase commutation sequencing.

Over the years of development of what may be referred to as the Petersen motor technology, greatly improved motor design flexibility has been realized. Designers of a broad variety of motor driven products including household implements and appliances, tools, pumps, fans and the like as well as more complex systems such as disc drives now are afforded an expanded configuration flexibility utilizing the new brushless motor systems. No longer are such designers limited to the essentially “off-the-shelf” motor varieties as listed in the catalogues of motor manufacturers. Now, motor designs may become components of and compliment the product itself in an expanded system design approach.

During the recent past, considerable interest has been manifested by motor designers in the utilization of magnetically “soft” processed ferromagnetic particles in conjunction with pressed powder technology as a substitute for the conventional laminar steel core components of motors. So structured, when utilized as a motor stator core component, the product can exhibit very low eddy current loss which represents a highly desirable feature, particularly as higher motor speeds and resultant core switching speeds are called for. As a further advantage, for example, in the control of cost, the pressed powder assemblies may be net shaped wherein many intermediate manufacturing steps and quality considerations are avoided. Also, tooling costs associated with this pressed powder fabrication are substantially lower as compared with the corresponding tooling required for typical laminated steel fabrication. The desirable net shaping pressing approach provides a resultant magnetic particle structure that is 3-dimensional magnetically (isotropic) and avoids the difficulties encountered in the somewhat two-dimensional magnetic structure world of laminations. See generally U.S. Pat. No. 5,874,796 (supra).

The high promise of pressed powder components for motors and generators initially was considered compromised by a characteristic of the material wherein it exhibits relatively low permeability. However, Petersen, in U.S. Pat. No. 6,441,530, issued Aug. 27, 2000 entitled “D.C. PM Motor With A Stator Core Assembly Formed Of Pressure Shaped Processed Ferromagnetic Particles”, describes an improved architecture for pressed powder formed stators which accommodates for the above-noted lower permeability characteristics by maximizing field coupling efficiencies.

As the development of pressed powder stator structures for electrodynamic devices such as motors and generators has progressed, investigators have undertaken the design of larger, higher power systems. This necessarily has lead to a concomitant call for larger press molded structures. The associated molding process calls for press pressures adequate to evolve requite material densities to gain adequate electrical properties. To achieve those densities, press pressures are needed in the 40 tons per square inch to 50 tons per square inch range. As a consequence the powdered metal pressing industry suggest that the design of molded parts exhibit aspect ratios (width or thickness to length in the direction of pressing) equal to or less than about 1:5. Thus as the length of stator core component structures increase, their thickness must increase to an extent that a resultant shape becomes so enlarged in widthwise cross section as to defeat the design goal, with attendant loss of both the economies of cost and enhanced performance associated with this emerging pressed powder technology.

BRIEF SUMMARY OF THE INVENTION

The present invention is addressed to electrodynamic apparatus and a method of manufacturing the stator core assemblies thereof utilizing press powder technologies wherein requisite stator core material densities are achieved while part thicknesses and volumes are retained within desirable dimensional limits. Requisite ratios of component widths or thicknesses to corresponding lengths are maintained in proper combinations while minimizing thicknesses of core structures through the employment of two or more stator core modules or components which, following their press forming, are selectively combined to define a sequence of module core components over which field windings are positioned. Because the stator core modules may be geometrically identical, tooling costs may be conserved through employment, in effect, of a single mold to produce them.

In one embodiment of the invention, paired stator core modules are combined in tandem along the axis of the electrodynamic apparatus to achieve an enhanced functional capacity while minimizing the diametric extent of the device within which they perform. With this arrangement, two or more sets of phase defining field windings are utilized with wire diameters of smaller extent. These phase defining windings advantageously then may be combined for simultaneous excitation through employment of a series or parallel electrical interconnection.

Where stator assembly sizes are called for which are large, the stator core modules may be press formed in segmented fashion. The resulting segments then may be combined in mutually abutting fashion to form the stator modules. Further, the configuration of these segments may be selected such that segments otherwise aligned within paired stator modules can be pre-wound with field winding elements prior to being abuttably joined together.

A convenient feature of the stator assemblies resides in the utilization of electrically insulative shields positioned over the mutually outwardly disposed winding support surfaces of field winding core portions of the stator pole core member. In general, the pole core members are formed with wire receiver troughs within which field windings are retained. To facilitate the circuit association of the windings from pole-to-pole within the stator assembly, the insulative shield may be configured to extend outwardly to define an outwardly open wire receiving channel adjacent the inner surface of an associated back iron region of the stator structure. The stator structures revealed in the embodiments presented herein are all shown in the classical inward facing salient stator pole configuration. This should not be considered a limitation as U.S. Pat. No. 6,441,530 (supra) illustrates both inward and outward facing stators and is incorporated by reference herewith.

Other objects of the invention will, in part, be obvious and will, in part, appear hereinafter.

The invention, accordingly, comprises the apparatus and method possessing the construction, combination of elements, arrangement of parts and steps which are exemplified in the following detailed description.

For a fuller understanding of the nature and objects of the invention, reference should be made to the following detailed description taken in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of electrodynamic apparatus incorporating the features of the invention;

FIG. 2 is a sectional view taken through the plane 2-2 shown in FIG. 1;

FIG. 3 is a sectional view taken through the plane 3-3 shown in FIG. 2;

FIG. 3A is a partial top view of an alternate configuration for a core member flux interaction region;

FIG. 4 is a perspective view of a core component configured in accordance with the invention;

FIG. 5 is an exploded view showing a combination of four of the components shown in FIG. 4;

FIG. 6 is an electrical schematic diagram showing the parallel association of two “Y” winding configurations employed with the stator structure of FIG. 5;

FIG. 7 is a schematic representation of a phase winding configuration;

FIG. 8 is a partial sectional view of electrodynamic apparatus according to the invention showing interpole winding geometry;

FIG. 9 is a sectional view of another electrodynamic apparatus structuring according to the invention;

FIG. 10 is a sectional view of another electrodynamic apparatus stator component structuring according to the invention;

FIG. 11 is a sectional view of a electrodynamic apparatus structure having a segmented stator core architecture;

FIG. 12 is a perspective view of a stator core component architecture shown in FIG. 11;

FIG. 13 is a sectional view of apparatus according to the invention showing a multi-segmented stator core component architecture; and

FIG. 14 is a perspective view of a stator core component as depicted in connection with FIG. 13.

DETAILED DESCRIPTION OF THE INVENTION

In the discourse to follow radially salient pole stator structures and the techniques of their formation and assembly are described in conjunction with d.c. PM motors having an architecture for deriving relatively higher power outputs, for example, about 250 watts and above. The structuring and techniques apply additionally to other forms of motors such as doubly salient pole motors and to electricity generators. Thus, the term “electrodynamic apparatus” is utilized with the meaning that it incorporates motors and generators employing the noted techniques of stator formation. In developing such electrodynamic devices utilizing magnetically soft composite pressed powder technology for stator construction the developer will establish a variety of dimensional parameters for electrical reasons establishing, for instance, appropriate material thicknesses to achieve flux transfer and avoidance of saturation. These electrical criteria are generated by calculation. When those requisite thicknesses are so established with judicious safety factors, the utilization of pressed powder material above and beyond those thicknesses will contribute only to weight and cost without improvement in device performance. Once these dimensional parameters are established, then the developer is confronted with the mandates of the powder metal pressing industry requiring molded part aspect ratios calling for structural thicknesses well beyond those necessary for electrical performance criteria.

Looking to FIG. 1, a d.c. PM motor configured according to the precepts of the invention is represented generally at 10. Motor 10 is formed with a cylindrical outer sleeve 12 formed, for example, of aluminum or plastic to which is connected cylindrical end caps 14 and 16. These caps 14 and 16 are retained in place by three hex head machine screws 18-20. Extending from an opening 22 within end cap 14 is a rotor shaft 24.

Referring to FIG. 2, device 10 is revealed in section. Rotor shaft 24 is seen disposed symmetrically about a rotor axis 26. The shaft 24 is necked down to define an annular shoulder 28 which engages the inner race of a ball bearing 30, which in turn, is seated within a cylindrical bearing cavity 32 formed within end cap 14. In similar fashion, the opposite end of shaft 24 is necked down to define an annular shoulder 34 which abuttably engages the inner race of a ball bearing 36. The outer race of ball bearing 36, in turn, is biased inwardly by a wavy washer 40 interposed between bearing 36 and bearing cavity surface 42.

Shaft 24 supports a rotor represented generally at 44 which is formed having a cylindrical core 46 formed of aluminum extending to an outer cylindrical surface 48. Coupled with that surface 48 is a cylindrical back iron 50 formed of ferrous material and extending to a cylindrical back iron surface 52. Surface 52, in turn, supports a cylindrical radially magnetized permanent magnet 54 which extends to flux confronting surfaces 56. Those flux confronting surfaces provide, in this embodiment, a sequence of six magnetic regions of alternating polarity generally extending in parallel with the rotor axis 26.

Additionally supported for rotation upon shaft 24 is a polymeric annular disc 58 which rotationally supports an annularly-shaped sequence of sensible system permanent magnets shown in cross section at 60. The annular magnets sequence 60 is shown mounted within an annular steel back iron 62 supported, in turn, upon an annular shoulder 64 formed within disc 58. Mounted internally upon end cap 16 is a printed circuit board 66 which functions to carry an integrated circuit 68 along with appropriate driver transistors and one or more Hall effect sensors as shown at 70. Sensor 70 is positioned for magnetic field response to the magnetic regions of sensible system magnet 60.

An annular stator assembly is represented generally at 80. Assembly 80 is formed using a material composed of magnetically soft pressure shaped processed ferromagnetic particles which are generally mutually insulatively associated. These materials such as Somaloy 500, are sometimes referred to as involving soft magnetic composite technology and are marketed, inter alia, by North American Hoganas, Inc. of Hollsopple, Pa. Assembly 80 is configured as a radial salient pole stator having nine, angularly spaced apart identical stator pole core members. Looking additionally to FIG. 3, these core members are represented in general at 82 a-82 i. Core members 82 a-82 i are formed integrally with and extend radially inwardly from a portion of a cylindrically shaped back iron 84 having a widthwise extent identified by paired arrows 86. Extending radially inwardly from back iron 84 are nine winding core portions 88 a-88 i of the stator pole core members. The widthwise dimension or thickness of these winding core portions 88 a-88 i are identified at paired arrows 90. Winding core portions 88 a-88 i extend radially inwardly to respective integrally formed flux interaction portions 92 a-92 i. The widthwise extent or thickness of these flux interaction portions is represented at paired arrows 94. Depending on the arc length of the flux interaction portions relative to the widthwise extent of the winding core portions the flux interaction portions on 92 a-i on either side of the widthwise extent of the winding core portions may be tapered to a lesser widthwise extent at the extremes of its arcuate extent as shown in FIG. 3A. These flux interaction portions extend to respective arcuate flux interaction surfaces 96 a-96 i which are spaced from flux confronting surface 56 of rotor 44 to define a functioning or working gap 98. Regions as at 92″ are more typical when the air gap between adjacent stator pole tips is less than twice the distance from the flux interaction surface to the magnet back iron. FIG. 3 reveals that the permanent magnet feature of rotor 44 is formed with six magnetic regions extending along the motor axis. These regions are identified at 100 a-100 f.

Core members 82 a-82 i and back iron 84 are not formed as a unitary part in their axial plane. Were they to be so formed, the widthwise dimensions required to meet the pressing criteria for pressure shaped processed ferromagnetic particles would increase significantly causing the resulting structure to be less desirable for its intended electrodynamic function. In accordance with the precepts of the invention, the back iron and core members are constructed, for the instant embodiment, as four identically structured modules, each of which is formed meeting press forming criteria and optimum electrical criteria. In this regard, the ratio of each of the noted predetermined widthwise or thickness dimensions with respect to their length in the direction of pressing is equal to or less than a ratio of about 1 to 5. Looking to FIG. 4, a perspective view of the uppermost one of these modules is represented in general at 110. In the following descriptions top and bottom surfaces of a stator module or component such as seen in perspective in FIG. 4 are defined as the axial end surfaces of each component. In an assembly of components these surfaces form outward facing and inward facing surfaces of an electrodynamic device. In general, the term “bottom is used in an inward sense, and the term “top” is used in an outward sense. The terms “component” or “module” as used herein are intended to mean not only identical components but components having different configurations, for instance, with stator core portions made from different molds. Module 110 is formed with a back iron portion 84′ which extends from a back iron top surface region 116′ a predetermined length l₁ (press direction), to a back iron bottom surface region 118′. That length, l₁, is determined with respect to the wall thickness regions 86, 90 and 94 and noted high pressure pressing criteria. In similar fashion, the flux interaction portions, which are now identified generally at 92′, for module 110 extend from flux interaction top surface regions certain of which are identified at 120′ and extend the same length, l₁, to a flux interaction bottom surface region is which identified at 122′. As revealed in FIGS. 2 and 4, back iron top surface region 116′ and flux interaction top surface region 120′ reside in a common plane which is perpendicular to the axis 26. In similar fashion, back iron bottom surface region 118′ and flux interaction bottom surface region 122′ reside in a common plane which is parallel with the top surface region common plane. FIG. 4 also reveals the presence of top and bottom alignment notches shown respectively at 124′ and 126′.

Certain of the winding core portions of module 110 are identified in general in FIG. 4 at 88′. Looking additionally to FIG. 2, these winding core portions 88′ extend from a winding core top surface region certain of which are identified at 128′ a length l₂ to a winding core bottom surface region certain of which are revealed at 130′. FIG. 4 reveals that the winding core top surface regions 128′ reside in a common plane and that the edges thereof are chamfered to facilitate the mounting of field winding wire thereover. In contrast, the winding core bottom surface regions 130′ need not be chamfered inasmuch as they will be seen not to receive or support field winding wire. FIGS. 2 and 4 further reveal that the winding core top surface regions 128′ are recessed inwardly from the back iron top surface regions 116′ and flux interaction top surface regions 120′ to define receiver troughs certain of which are identified at 132′. Receiver troughs 132′ further are defined by a radially inwardly slopping surface 134′ formed within the module back iron portion 84′. In similar fashion, a radially outward slopping surface, certain of which are identified at 136′ is formed in each of the stator pole core member flux interaction portions.

Looking additionally to FIG. 5, it may be observed that stator assembly 80 is configured with four modules which are shown as being identified for illustrative purposes and thus are configured as described in conjunction with FIG. 4. Accordingly, not only do the modules have dimensional aspect ratios which permit their compression molding and practical shapes, but also they are economically fabricable inasmuch as for the present embodiment a singular molding tool is employed. The four modules are revealed in FIGS. 2 and 5 at 110-113. To facilitate the identification of the identical portions of these modules, such elements are numerically identified in the same fashion as provided in FIG. 4 but with priming provided for modules 110 through 113 respectively extending from a single prime to four primes. Modules 111 and 112 may be referred to as medial modules with medial stator pole core members of medial dimensions. Note in FIG. 5 that modules 110 and 111 are paired such that, for example, the back iron top surface regions 116′ and 116″ as well as the corresponding flux interaction top surface regions 120′ and 120″ face mutually outwardly. The same mutual orientation is provided in conjunction with components 112 and 113. Mutual angular alignment or slight misalignment of all of the modules 110-113 is provided by three alignment pins 138-140. In this regard, alignment pin 138 engages notches 126′ and 126″. Aligning pin 139 engages notches 124″ and 124″′, and alignment pin 140 engages notches 126″′ and 126″″.

Returning to FIG. 2, modules 110-113 are retained in mutual abutment and alignment by combination of cylindrical sleeve 12, end caps 14 and 16 and their mutual coupling by machine screws 18-20. For the device design at hand, a mutual contacting abutment between paired modules as at 110 and 111 or 112 and 113 is not a requisite arrangement. In this regard, the paired components will perform appropriately if slightly separated in an axial sense with shock absorbing materials or the like.

FIG. 2 illustrates, inter alia, stator pole core member 82 g in section as well as a non-sectional view of core member 82 c. These core members, as described above, are configured with modules 110-113 in paired and stacked relationship. Note in FIG. 2 that the winding core portions of these core members support two as opposed to a single field winding. In this regard, core member 82 g is seen supporting field windings 150 g and 152 g. Field winding 150 g is wound about the receiver troughs 132′ and 132″ of respective modules 110 and 111, while field winding 152 g is wound about receiver troughs 132″′ and 132″″ of respective modules 112 and 113. Similarly, field winding 150 c is seen wound about receiver troughs 132′ and 132″ at core member 82 c and additionally the field winding 152 c is shown wound about receiver troughs 132″′ and 132″″ of that core member. Conventional brushless motor architecture will incorporate a single winding for each core member as at 82 a-82 i. Where the core members are formed, for example, utilizing conventional thin laminations, larger gage field winding wire is necessitated because of the single winding per stator pole member and the accumulated winding bundle will protrude above and below the core members. By virtue of the utilization of net shaped modules 110-113, receiver troughs as at 132′-132″″ can be employed which fully incorporate the field winding wire bundles, i.e., the outermost level of field winding wire is spaced inwardly from back iron and flux interaction outer tip or top surface regions as shown respectively at 116′-116″″ and 120′-120″″. Because two windings are incorporated with each core member 82 a-82 i and if the windings are connected in parallel the current carried by each field winding is, in effect, reduced by 50% and, thus, the gauge thickness of the wire may be reduced proportionally. Also the machine winding time is greatly reduced because the axial length over which the winder must reach is cut in half in this embodiment.

FIGS. 2 and 3 reveal that an electrically insulative, polymeric shield is positioned within each of the receiver troughs 132′-132″″ intermediate the winding core and an associated field winding. In this regard, shields are shown in section in FIG. 3 at 154 a-154 i. Shield 154 g is revealed in position over receiving trough 132′ in FIG. 2. Similarly, shield 154 c also is shown associated with module 110. FIG. 2 reveals shields 156 c and 156 g located within receiver trough 132″ in conjunction with module 111. Shields 158 c and 158 g are revealed as installed within receiver troughs 132″′; and shields 160 c and 160 g are shown installed within receiver troughs 132″″. FIG. 2 further reveals that that portion of the shield adjacent the back iron portion of the stator core member extends to an outer tip or top surface region and defines an outwardly open channel configured to carry lead out and lead in components of field winding wire. For a multiphase architecture, it is necessary to interconnect these windings and thus a non-interfering intercommunicating arrangement be developed. Note, that channels 162 c and 162 g are formed within respective shields 154 c and 154 g. Similarly, outwardly open channels are shown at 164 c within shield 156 c and at 164 g in shield 156 g. An outwardly open channel is seen at 166 c in shield 158 c and at 166 g in shield 158 g. Finally, an outwardly open channel 168 c is formed within shield 160 c and an outwardly open channel 168 g is seen formed within shield 160 g.

The receiving troughs and associated shields are configured to carry windings below the noted tip or top surface regions of the back iron portions and flux interaction portions and thus permit module stackability. Additionally, FIGS. 2 and 5 reveal another feature of the device architecture, note that the winding core bottom surface regions identified at 130′-130″″ are recessed inwardly from the associated flux interaction bottom surface regions 122′-122″″ and back iron bottom surface regions 118′-118″″. These recesses are provided to achieve the desired amount of winding core cross-section area. It may be recalled that the design of the motors calls for utilizing thicknesses and lengths for the modules 110-113 which are appropriate to avoid flux saturation phenomena and to incorporate a suitable safety factor. However, beyond those criteria no additional materials are utilized. Therefore, recesses may not be necessary and should not be considered limiting. Accordingly, the modular stacking design at hand within modules 110-113 is one permitting a highly efficient utilization of the pressure shaped processed ferromagnetic particles.

Turning now to the configuration of the windings 150 a-150 i provided with modules 110 and 111, reference is made to FIG. 6. In the figure, the windings at modules 110-111 are represented in general at 150 and the windings associated with modules 112 and 113 are represented in general at 152. The three phases of these windings further are identified at branches A, B, and C and the winding positions are identified by the numeration 1, 2, and 3. These “Y” windings are connected in parallel. In this regard, note that phase A of windings 150 and 152 are commonly connected to line 180 which additionally is labeled as a phase “A”. Phase B of windings 150 is coupled to line 182, while the corresponding phase B of windings 152 are coupled via line 184 to line 182. Finally, phase C of windings 150 is coupled to line 186 while the corresponding phase C of windings 152 is coupled to line 186 via line 188. Thus, phases A, B, and C at respective lines 180, 182 and 186 extend to the printed circuit board 66 as shown in FIG. 2.

Referring to FIG. 7, the geometric aspect for the winding of one of these Y structures, for example, at 152 is schematically revealed. In the figure, the nine windings are identified in the manner of FIG. 6, i.e., being shown as C1, C2, C3, A1, A2, A3, and B1, B2, and B3. Lines 180, 182, and 186 are reproduced in FIG. 7 and the windings are represented showing clockwise rotation of the wire from the start lead to the center tap where the windings join in common as the center of the Y architecture. Now looking to the partial sectional end view of the motor 10 in FIG. 8, windings A2 and B2 are represented. The figure represents these windings from a schematic standpoint in the direction represented by the viewing directional arrow 190 in FIG. 7. Referring additionally to that figure, the start of the winding B2 and, correspondingly the finish of winding B1 is represented at 182′ in both figures. Note that the winding is within outwardly open channel 168 e. Correspondingly, the start of winding A2 and correspondingly the finish of winding A1 is represented at 180′ extending from channel 168 e. The finish of winding A2 is represented in both figures at 180″ while the start of winding B2 again is identified at 182′ exiting from channel 168 f. Finally, the finish of winding B2 is represented in FIGS. 7 and 8 at 182″. The manufacturing procedures for carrying out these windings are substantially simplified and improved by virtue of the reduced axial winding length for each “Y” winding 152 and 150 as provided by the combination of modules 112 and 113 and 110 and 111.

This approach of achieving higher power motors through the combining of components or modules to form the field wound stator is uniquely suited to powder metal technology. Since the module design is optimized for uniting the requirements of the powder metal pressing industry and the electrical requirements of the motor design under consideration the total number of modules may vary. Also, the stacking ability of the modules yields a versatility to the motor design unavailable with a typical steel lamination motor design. Referring to FIG. 9, a version of the motor or electrodynamic apparatus limited to two modules is represented in general at 200. The similarity of the architecture of device 200 with that of electrodynamic apparatus or motor 10 becomes immediately apparent. In this regard, the motor is configured with an aluminum cylindrical sleeve 202, the ends of which are joined to cylindrical end caps 204 and 206. A bearing 208 is mounted within end cap 204 adjacent a shaft opening 210. Similarly, a bearing 212 is installed within end cap 206 adjacent opening 214. Bearings 208 and 212 support motor shaft 213, their inner raceways being rotatably engaged with respective shoulders 216 and 218 of the shaft. Shaft 213 is disposed about axis 280. A wavy washer 220 loads the outer race of bearing 212 into appropriate position. Shaft 213 supports a rotor represented generally at 222 formed having an aluminum inner core 224, a cylindrical back iron 226 and cylindrical permanent magnet or rotor pole region 228 extending outwardly to a cylindrical flux confronting surface 230. The assemblage of end caps 204 and 206, sleeve 202 and the shaft 213 is retained together, as before, by a sequence of machine screws, one of which is revealed at 232.

Motor 200 is configured with an annular stator assembly represented generally at 234, the stator portion of which is formed of two annular modules formed of pressure shaped processed ferromagnetic particles and here represented in general at 236 and 237. Note that the profiles of components 236 and 237 are identical to those described earlier at 110 and 111 or 112 and 113. Using the identifying convention of the earlier figures, for a nine stator pole embodiment, stator pole core members 240 c and 240 g of module 236 are revealed. In similar fashion, core members 242 c and 242 g are illustrated in connection with module 237. As before, each of these modules is net shaped with back iron portions as shown respectively at 244 c, 244 g and 246 c, 246 g. The back iron portions are integrally formed with the winding core portions of the stator pole core members as seen at 248 g and 250 g. Those winding core portions are, in turn, integrally formed with flux interaction portions as at 252 c, 252 g and 254 c, 254 g. These flux interaction portions extend to arcuate flux interaction surfaces as at 256 c, 256 g in the case of module 236 and at 258 c, 258 g for the case of module 237. The surfaces define, with the flux confronting surface 230 of rotor 222 a functioning or working air gap 260. Note that as in the case of earlier embodiments, both the back iron portions and flux interaction portions of the core components extend to coplanar top and bottom surface regions. The bottom surface disposed tip regions are located in mutual adjacency and alignment while the top surface regions extend to define receiver troughs as represented at 262 c, 262 g for module 236 and at 264 c, 264 g as illustrated in connection with module 237. In each receiver trough, the winding core portions support a polymeric electrically insulative shield, each configured in the manner described above in connection with motor 10. Note that polymeric shields 266 c, 266 g are positioned within respective receiver troughs 262 c and 262 g while polymeric shields 268 c, 268 g are located within respective receiver troughs 264 c, 264 g. Field windings are shown, as before, at 270 c, 270 g, the winding starts and finishes thereof being carried about the motor via outwardly open channels formed within the shields 266 c, 266 g and 268 c, 268 g. Those open channels are represented, for instant illustration at 272 c, 272 g and 274 c, 274 g. As before, motor 200 incorporates a sensible system having a disc form and represented generally at 276 which performs in conjunction with printed circuit board mounted control circuit sensors. Such a printed circuit board is represented in general at 278. A preferred sensible system and sensor implementation for the motor as disclosed herein is described in a co-pending application for United States patent by Petersen entitled “Multi-Phase Motors With Single Point Sensing Based Commutation” (supra).

As in the previous embodiment, winding core regions 284 g and 286 g are recessed to help achieve the desired electrical characteristics while retaining a suitable safety factor in overall winding core area. Additionally, some material and weight economies are also achieved. It should be noted that the recess 284 g and 286 g as well as recesses in the winding core bottom surface; 130′-130″″ in the previous equipment are not required for proper or efficient motor assembly and may not be a necessary feature when designing for the optimum electrical characteristics, but are shown as an optional design feature available with pressed powder technology and suitable for many applications.

Referring to FIG. 10, a motor or electrodynamic device represented generally at 300 is shown having an elongated architecture extending along its motor axis 302. Device 300 represents a design wherein a stator assembly and associated rotor are of greater lengthwise extent along axis 302 as compared with the lengthwise extent of motor 200 along axis 280 (FIG. 9). To achieve this desired extra length without excessive widthwise extents of the stator core components mandated by the above discussed pressed molding procedures, the stator is formed with three free-form components with lengths along axis 302 suited to achieve appropriate net shaping without excess thickness. As in the case of motors or electrodynamic devices 10 and 200, motor 300 is formed with a aluminum cylindrical sleeve 304 the axially oppositely disposed ends of which are coupled with identical end caps 306 and 308. End cap 306 is configured to support a bearing 310 at a shaft opening 312 and, correspondingly, a bearing 314 is mounted within end cap 308 adjacent opening 316. Bearings 310 and 314 support a rotor shaft 318, the shoulders of which at 320 and 322 are engageable with the bearing internal raceways. A wavy washer 324 functions to load the external race of bearing 314 inwardly. Shaft 318 supports a rotor represented generally at 326 having a cylindrical aluminum inner core 328, the outer cylindrical surface of which supports a cylindrical rotor back iron 330. Rotor back iron 330, in turn, supports cylindrical permanent magnet 332 defining a sequence of, for example, six rotor poles and providing a flux confronting surface 334. As before, the device assemblage is interconnected utilizing a sequence of machine screws, one of which is revealed at 336.

The stator assembly for motor or device 300 is represented generally at 338 and is seen to be structured having three pre-formed stator core module components 340-342. Again utilizing the descriptive approach employed with motor or device 10 in FIG. 2, stator pole core members 344 c, 344 g are shown in conjunction with module component 340. Stator pole core members 346 c, 346 g are shown associated with module component 341, and stator pole core members 348 c, 348 g are shown associated with module component 342. Core members 344 c, 344 g are shown formed integrally with respective back iron portions 350 c, 350 g. Core members 346 c, 346 g are shown formed integrally with respective back iron portions 352 c, 352 g, and core members 348 c, 348 g are shown formed integrally with respective back iron portions 354 c, 354 g. These back iron portions are integrally formed with winding core portions extending therefrom. In this regard, core member 344 g is shown having a winding core portion 356 g. Core member 346 g is shown having a winding core portion 358 g and core member 348 g is shown having an integrally formed winding core portion 360 g. These winding core regions are formed integrally with flux interaction portions. In this regard, core members 344 c, 344 g incorporate respective flux interaction portions 362 c, 362 g. Core members 346 c, 346 g incorporate respective flux interaction portions 364 c, 364 g, and core members 348 c, 348 g incorporate respective flux interaction portions 366 c, 366 g. The flux interaction portions extend to define arcuate flux interactions surfaces. In this regard, flux interaction portions 362 c, 362 g define respective flux interaction surfaces 368 c, 368 g. Flux interaction portions 364 c, 364 g extend to form respective arcuate flux interaction surfaces 370 c, 370 g and flux interaction portions 366 c, 366 g extend to form respective flux interaction surfaces 372 c, 372 g. These flux interaction surfaces cooperate with the corresponding rotor flux confronting surface 334 to define a functional or working gap 374.

Each of the stator pole core members of each module 340-342 is configured with an inwardly depending receiver trough from each axial surface. For example, receiver troughs 376 c, 376 g and 388 g are formed within respective core members 344 c, 344 g of module 340. Centrally disposed core members as at 346 g also are formed having an identical receiver trough as represented at 378 g and 389 g, and core members 348 c, 348 g are seen to have respective receiver troughs 380 c, 380 g and 390 g. For the present embodiment electrically insulative polymeric shields are inserted over the winding core portion in the outboard or outwardly opening receiver troughs of the module assembly. In this regard, shields 382 c, 382 g are inserted within respective receiver troughs 376 c, 376 g and shields 384 c, 384 g are inserted within respective receiver troughs 380 c, 380 g. Shields 382 c and 384 c are seen to support a more elongate field winding 386 c. Similarly, shields 382 g and 384 g are seen to support field winding 386 g.

As illustrated on the C numerated side of FIG. 10 the field winding encompasses all three stator pole core members 344 c, 346 c and 348 c coupling them together magnetically. The figure also reveals the formation of recesses on the bottom surfaces of each of the end module stator pole core members and on both surfaces of the center module. For example, such recesses are revealed at 378 g, 388 g, 389 g and 390 g. As before, the recesses function to permit fabrication of the winding core regions to satisfy the electrical design requirements of the motor and to an extent sufficient to avoid saturation and provide a reasonable factor of safety. Note that the recesses formed on the top and bottom surface regions of the winding core portion of each core member of each stator module are identical in this embodiment.

Motor 300 also contains a sensible system represented as a disc at 392 which cooperates with a sensor arrangement and control circuit at a printed circuit board 394.

In the embodiment presented herein the individual stator core modules can be purposely slightly angularly misaligned or skewed within the cylindrical outer sleeve resulting in an offset between adjacent stator pole core members of adjacently stacked core modules yet still permitting the winding operation to occur in the same manner as if each individual stator core module was perfectly angularly aligned. This misalignment can be used in certain motor designs to reduce the effects of cogging or detent torque where desirable or required.

As the instant electrodynamic apparatus structures reach larger sizes the module components forming the stator structure may themselves be segmented, again to accommodate for the severe molding requirements at hand as well as to facilitate the winding of field coils about the winding core regions. One such segmentation approach is illustrated in connection with FIGS. 11 and 12. Looking to FIG. 11, a motor represented generally at 400 is shown in a sectional portrayal similar to that seen in FIG. 3. In this regard, the section is taken through a module component represented generally at 402 and seen additionally in perspective fashion in FIG. 12. Component 402 is formed with nine stator pole core member assemblies represented generally at 404 a-404 i. Stator pole assemblies 404 a-404 i are formed with corresponding pressed powder net shaped stator pole core members represented generally at 406 a-406 i as seen additionally in FIG. 12. Each of the core members 406 a-406 i is formed, as before, integrally with back iron portions 408 a-408 i from which emanate the winding core portions shown respectively at 410 a-410 i which, in turn, are integrally formed with respective flux interaction portions 412 a-412 i. The flux interaction portions 412 a-412 i extend respectively to arcuate flux interaction surfaces 414 a-414 i. A rotor is represented generally at 416 structured in the same manner as rotor 44 described in connection with FIGS. 1-3. This rotor extends to a flux confronting surface and is spaced from flux interaction portions 412 a-412 i to define a working or functional gap 420. Component retention is provided by a sequence of machine screws in the same manner as described in connection with motor 10. In this regard, sectional representations of three such machine screws are provided at 421-423.

Note that component 402 is not net shaped as a unit but is pre-formed in three arc shaped segments which are joined together in mutual abutment at edge locations 426-428. This form of abutment is intimate and touching inasmuch as the resultant three segments reside in flux transfer communication. Three segments are maintained in their arch-like structural orientation by the outer cylindrical sleeve 430 seen in FIG. 11. The three segments, identified in general at 432-434 are seen in FIG. 11 to be associated with insulating sleeve and field winding combinations 436 a-436 i. Preferably, the field windings are mounted upon the stator pole core members 406 a-406 i as they exist in the segments 432-434. In certain rotor pole, stator pole, pair arrangements such as a nine pole stator and an eight pole rotor the three windings of each phase are wound on adjacent poles meaning A1, A2, A3, B1, B2, B3 and C1, C2, C3 as one proceeds around the stator. This winding form could be enhanced with the stator arrangement of FIGS. 11 and 12 since the multiple stacked core components or modules of a single phase could be pre-wound prior to assembly into sleeve 430.

Note additionally in FIG. 12 that alignment notches are provided, for example as shown at 438 and 440 in segment 433. The figure further reveals the provision of receiver troughs 442 a-442 i at respective winding core portions 410 a-410 i.

Looking to FIGS. 13 and 14, an architecture is presented wherein a single component is formed of nine segments in a nine stator pole assembly configuration. This form of construction would only be applicable on larger motor types since assembly of multiple segments is first required prior to assembly of the stacked modules to complete a single stator assembly such as shown in FIGS. 9 and 10. In FIG. 13, motor or device 500 is represented in sectional format in the manner of FIGS. 3 and 11. Correspondingly, FIG. 14 shows in perspective a multi-segmented module which is provided in conjunction with the sectional locations on the motor 500 shown in FIG. 13. Looking to that figure, motor or device 500 is seen to be comprised of nine distinct stator pole assemblies 504 a-504 i. As represented additionally in FIG. 14, these stator pole assemblies 504 a-504 i are configured with corresponding and respective stator pole core members 506 a-506 i. As before, each of the stator pole core members 506 a-506 i is formed integrally with a back iron portion as represented in FIG. 13 respectively at 508 a-508 i. Integrally formed therewith and extending radially inwardly from the back iron portions 508 a-508 i are respective winding core portions 510 a-510 i. These winding core portions which are recessed as seen in FIG. 14, extend radially inwardly to and are formed integrally with flux interaction portions shown respectively at 512 a-512 i. The flux interaction portions 512 a-512 i extend radially inwardly to define arcuate flux interaction surfaces shown respectively at 514 a-514 i.

The rotor of motor or device 500 is represented in general at 516 and is configured in the same manner as rotor 44 described in connection with FIGS. 2 and 3. The rotor extends radially outwardly to provide a flux confronting surface 518 which in turn, cooperates with flux interaction surfaces 514 a-514 i to define a working or functional gap 520. Each of the stator pole core members 506 a-506 i is provided with a polymeric electrically insulative shield over the winding core portion interfacing with the associated winding combination as shown in general at 522 a-522 i within respective stator pole assemblies 504 a-504 i.

FIGS. 13 and 14 reveal that the module 502 is formed of nine discrete segments, the edges of the back iron portions of which are abutted together in flux transfer relationship at nine locations shown at 524-532. Thus, each segment is configured with a singular component stator core assembly. In this regard, it may be recalled that at least two axially stacked modules are called for in this axially modular form of optimized large motor construction. As in the case of component 402 described in connection with FIGS. 11 and 12, the segments are assembled in compression along their back iron portions to evolve an arch form of structure exhibiting desirable structural integrity. The back iron components are retained in their appropriate orientation by cylindrical sleeve 544 seen in FIG. 13. As described in connection with motor 10, motor 400 module components, end caps and cylindrical sleeve are retained in position by a sequence of three machine screws, sectional representation of which are shown in FIG. 13 at 534-536. It should be noted that there are other suitable means of securing the final assembly of the end caps and the stator module assemblies other than the aforementioned machine screws and therefore their use in the embodiments presented herein should not be considered in a limiting sense. One segment, for example, that representing a back iron portion and a stator pole core member 506 e is configured having alignment notches as at 538 and 540 to aid in assembly of the entire stator core as described in connection with FIG. 5. Note additionally in FIG. 14 that the motor axial length of the winding core portions 510 a-510 i is diminished, inter alia, to define receiver troughs shown respectively at 542 a-542 i.

Since certain changes may be made in the above-described apparatus and method without departing from the scope of the invention herein involved, it is intended that all matter contained in the description thereof or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense. 

1-39. (canceled)
 40. A method for manufacturing a stator assembly for a multiphase electrodynamic apparatus having an axis, comprising the steps of: (a) providing a powdered metal pressing facility for producing by compressive molding a stator core module, said facility being configured to provide said stator core module as being formed of ferromagnetic particles which are generally mutually insulatively associated, and said stator core module comprising a back iron portion and a plurality of stator pole core members each formed integrally with said back iron portion said said back iron portion having a back iron widthwise extent and back iron length extending from a bottom surface to a top surface, said core members having a winding core portion with core widthwise extent and extending a core length between bottom and top winding core surfaces, and a flux interaction portion having an interaction widthwise extent, integrally formed with said winding core portion and extending an interaction length from a top surface to a bottom surface, said back iron widthwise extent and corresponding said back iron length, said winding core widthwise extent and corresponding said winding core length, and said interaction widthwise extent and corresponding said interaction length being selected to derive a said stator core module by said compressive molding wherein said particles of said stator core modules exhibit a density effective to achieve adequate operational permeability and avoidance of magnetic saturation under operating conditions; (b) molding at least a first and a second stator core module in a said powdered metal pressing facility; (c) symmetrically disposing said first and second stator core modules about said axis in a manner wherein said back iron portions are circumferentially aligned and said stator pole core members are axially aligned to an extent permitting stator pole winding to be applied over said axially aligned stator pole core members said winding core portion of said first and second stator core modules; (d) fixing said stator pole core members of said first and second stator core modules in such axially aligned orientation; and (e) providing a sequence of field windings each extending over and supported by the mutually outwardly disposed top surfaces of said winding core portions of said first and second stator core modules.
 41. The method of claim 40 wherein: said back iron widthwise extent and corresponding back iron length are selected in step (a) to respectively exhibit a ratio equal to or less than about 1 to
 5. 42. The method of claim 40 wherein: said winding core widthwise extent and corresponding winding core length are selected in step (a) to respectively exhibit a ratio equal to or less than about 1 to
 5. 43. The method of claim 40 wherein: said interaction widthwise extent and corresponding interaction length are selected in step (a) to respectively exhibit a ratio equal to or less than about 1 to
 5. 44. The method of claim 40 wherein: at least a third said stator core module is placed and aligned intermediate said first and second stator core modules; said field winding surmounting said winding core portions between said winding core portions of said first and second stator modules.
 45. The method of claim 40 wherein: said step (b) further comprises molding at least a third and a forth stator core module in a said powdered metal pressing facility; said step (c) further comprises symmetrically disposing said first, second, third and fourth stator core modules about said axis in a manner wherein said back iron portions are circumferentially aligned and said third and fourth stator core modules' stator pole core members are axially aligned to an extent permitting stator pole winding to be applied over said axially aligned stator pole core members said winding core portion of said third and fourth stator core modules; said step (d) further comprises fixing said stator pole core members of said third and fourth stator core modules in such axially aligned orientation; and said step (e) further comprises providing a sequence of field windings each extending over and supported by the mutually outwardly disposed top surfaces of said winding core portions of said third and fourth stator core modules, said first and second stator core modules being connected in series or parallel electrical interconnection with said third and fourth stator core modules.
 46. A method of enclosing a stator core module assembly comprising of two or more stator core modules each formed of pressure shaped ferromagnetic particles which are generally mutually insulatively associated comprising the steps of: (a) placing a rotor assembly central to said stator core modules; (b) affixing a first motor end cap over one end of the shaft of said rotor assembly and adjacent with an end surface of said stator core module assembly; (c) affixing a second motor end cap over the opposite end of said rotor shaft and adjacent with the other end of said stator core module assembly; and (d) installing two or more fastening devices through said rotor assembly from said first motor end cap to said second motor end cap and tightening said fastening devices such that the components of said stator core module assembly are firmly held in place and aligned.
 47. The method of claim 46 further comprising the step of: (e) installing a sleeve over the outside surface of said stator core module assembly intermediate said first motor end cap and said second motor end cap, said sleeve aligning and enclosing said stator core module assembly.
 48. The method of claim 46 wherein said step (d) further comprises installing said fastening devices as screws.
 49. The method of claim 46 wherein said step (d) further comprises installing said fastening devices as fastening rods. 